I recently installed OS Loved the new OS and features but found my berry kept restarting during calls, usually after just a couple of minutes into each call.

I then upgraded to OS suspecting that the older Beta might have been the cause but I had the same issues.

Having read other posts from happy 4.5 users and also reading that other users of different devices (I'm using an unlocked 8310 on UK O2 network) also suffered the same issue, I felt maybe 4.5 wasn't the issue after all. Most people were saying the only thing they could do to fix the issue is get their devices replaced. No one seemed to have an answer.

However, after literally hours and hours of trying different things the issue appears to be with BES on 4.5 (or at least, on an OS that is not supported by your carrier).

I replaced the battery, replaced the MicroSD card, swapped with SIM card, deleted languages, removed the Vendor.xml file, re-initiated the voice-dialing feature, cleared my cache, freed up memory, wiped my Berry and reinstalled the OS 4.5 from fresh, deleted service books - just about everything people offered advice on. Nothing worked

When I did re-install 4.5 I found the solution was fixed - I tested endlessly making calls and non of them dropped... and the device never restarted expectantly UNTIL... I activated my device on BES. Then the issue came back.

It seems that if you're using an operating system in Beta (which ALL 4.5 os's are at the moment, even the Vodafone release) on BES (the Enterprise version for BlackBerry), your device doesn't like it and will keep re-starting during calls.

I then tried to downgrade to my network's official latest release but found even the Wipe BlackBerry option (Options > Security > General > [OPTION: Wipe Handheld]), once re-installed and activated again on BES didn't do the job.

TO FIX THE ISSUE you need to completely remove your device using the JL_Cmder v1.9.0 application and then install your network's official OS release.

To do this, follow this useful link: How do I wipe the BlackBerry using Jl Cmder? - BlackBerryFAQ

I really hope this helps - my device is now working brilliantly and endless enjoyable calls without it restarting. I hope your experience is the same